passport gauge question
 

I purchased a 95 passport about 4 months ago and the voltmeter and oil pressure gauge stayed in the same spot until just the other day. Now they both fluctuate and they both started to do so at the same time. What could be the cause of this? Also, not long before this it started making a strange kind of jingling sound That would last a few minutes after firing up. This noise would occur whether the engine was hot or cold and would stop momentarily when brake was applied and continue with acceleration. Possibly both are connected?